Automated musical instruments, such as pianos, are well known in the art. Such instruments are typically acoustic instruments that use mechanical actuators to operate the instrument. The actuators receive commands of articulation events or music sequences to control or play the instrument. The music sequences are delivered to the instrument by a controller. There have been a number of attempts to have an automated instrument play in synchronization or accompaniment with a prerecorded CD or hard drive. Such attempts are described in U.S. Pat. Nos. 5,138,925, 5,300,725, 5,148,419 and 5,313,011. In order allow for synchronous play, those previous attempts rely upon timing information presented on a sub-channel of the CD to provide a common time frame for both the music sequences and the CD audio to reference. While such an arrangement is sufficient, it suffers from the limited resolution offered by the timing information of the CD sub-channel. The timing information of the CD sub-channel has a period or resolution of 13 milliseconds, which is not accurate enough for some piano sequences. The present invention described herein uses the timing inherent in the CD audio data as the time reference. By the use of this technique, the timing can have a period or resolution of 22.7 microseconds based upon the sample rate of 44.1 kHz of the digital audio data of the CD. One will recognize that this technique can be applied to any digital audio data, not just data on a CD. For instance, the technique may be applied to MP3, WAV or other popular digital media files.
While listening to the automated instrument playing alone is entertaining for the user, some users desire to have the instrument play along with a commercial recording of a musical selection, thus allowing the user to experience the recorded selection accompanied by a live automated instrument.
In some early products for playing an automated piano in synchronism with a CD, the CD media contained music sequences that were pre-synchronized to a digital accompaniment music track encoded as linear PCM. For instance, the audio music track would be encoded as PCM on the left channel of the CD, and the music sequence, encoded as MIDI, would be encoded on the right channel. In the invention described herein, the system utilizes off the shelf commercially recorded CD, or other digital audio data such as MP3 files, and music sequences specifically authored to play in synchronism with the musical selections on the media. The music sequences are generally MIDI files stored on removable media such as SD cards and the like. One skilled in the art will recognize that there are many ways to deliver the music sequences, such as MIDI files, to the consumer and ultimately to the controller of the automated musical instrument, and SD cards are but one example. Likewise, the MP3 or other digital audio data can be stored in any number of media, including optical discs, hard drives, SD cards, Compact Flash cards or any other media suitable for storing digital data.